MODIFICATIONS IN THE RATE OF ATP HYDROLYSIS AT VARYING pH LEVELS DUE TO ACTIVITY-SPECIFIC TRAINING

Abstract

387 Athletic performance relies heavily on the rate of ATP hydrolysis. Traditionally, the accumulation of lactate and the consequent decline in pH within the muscle are factors regarded as contributory to a reduction in the rate of ATPase activity. This can lead to the development of muscular fatigue. However, utilization of high-intensity training techniques appears to be effective in attenuating the decline in enzymatic function seen with decreases of intracellular pH. Thirty adult Sprague-Dawley rats (≅50 days old) were placed in a sprint-training (ST), endurance-training (ET) or sedentary control group (CG). Each training condition was 10 weeks in duration. At the completion of training, the rats were sacrificed and the gastrocnemius and soleus muscles were removed. Muscle fibers were isolated from each muscle and stripped of their sarcolemma and sarcoplasmic reticulum using 1% triton X-100. The skinned muscle fibers were analyzed for ATPase activity at pH levels of 6.5, 7.0, and 7.5 using a fluorescence technique. ANOVAs were performed on the data to evaluate differences in ATPase activity for each training condition at each pH as unique observations. Duncan's multiple range post hoc tests were used to identify any statistical differences. The ATPase activity of the ST rat gastrocnemius muscle increased significantly as pH declined (p<.05). ATPase activity was also significantly greater (p<.05) at a pH of 6.5 for the ST animals than for any pH level in the ET and CG rats. The soleus muscle of the ST rats showed similar results with its greatest ATPase activity at a pH of 6.5 (p<.05). Additionally, the ATPase at pH=6.5 for the ST group was significantly higher (p<.05) than the ATPase activity of the ET and CG soleus muscle at a pH of 7.5. These data support the hypothesis that enzymatic activity can be modified to adapt to the disturbances in internal environment dictated by specific training patterns. They also present one mechanism that may account for the ability of the sprint athlete to maintain power outputs at[H+] which would be exhaustive to endurance-trained or sedentary individuals.